Reaching 90 without dementia doesn’t mean you’re in the clear

People who reach their 90s without developing dementia might appear to have avoided cognitive decline, but recent research suggests dementia risk remains a concern in this age group. A study led by UC Davis Health and Kaiser Permanente, published in The Lancet Healthy Longevity, analyzed data from over 800 participants aged 90 and above.

The research highlighted significant differences in dementia risk based on sex, race, ethnicity, and genetics. Women in their 90s had about twice the dementia risk compared to men, and black and Hispanic participants faced a 75% higher dementia risk than Asian participants. The protective APOE2 gene, which is associated with a lower likelihood of Alzheimer's disease, showed a 60% lower dementia risk among those who carried it, even beyond age 90.

However, APOE4, a gene linked to increased Alzheimer's risk, had a more complex impact. In general, it did not significantly raise dementia incidence, but among men and black participants, APOE4 was associated with higher dementia risk. The study also revealed that some individuals with established dementia risk factors, like hypertension and high cholesterol, remained cognitively healthy in their 90s.

Researchers stress that these findings emphasize the importance of considering individual risk factors when assessing dementia risk in older adults, as simply assuming someone in their 90s is immune to dementia based on their overall risk profile may be inaccurate.